The Gibraltar "Choke Point"

Gibraltar is a British Overseas Territory located on the southern end of the Iberian Peninsula. It has an area of 6.7 km² (2.6 sq mi) and shares its northern border with Spain. The Rock of Gibraltar is the major landmark of the region. At its foot is a densely populated city area, home to over 30,000 Gibraltarians and other nationalities.

                                        Gibraltar Airport terminal

An Anglo-Dutch force captured Gibraltar from Spain in 1704 during the War of the Spanish Succession on behalf of the Habsburg claim to the Spanish throne. The territory was subsequently ceded to Great Britain "in perpetuity" under the Treaty of Utrecht in 1713. During World War II it was an important base for the Royal Navy as it controlled the entrance and exit to the Mediterranean Sea, which is only eight miles (13 km) wide at this naval "choke point" and remains strategically important to this day with half the world's seaborne trade passing through the strait. Today Gibraltar's economy is based largely on tourism, online gambling, financial services, and shipping.

The sovereignty of Gibraltar is a major point of contention in Anglo-Spanish relations as Spain asserts a claim to the territory. Gibraltarians overwhelmingly rejected proposals for Spanish sovereignty in a 1967 referendum and again in 2002. Under the Gibraltar constitution of 2006, Gibraltar governs its own affairs, though some powers, such as defense and foreign relations, remain the responsibility of the British government.

Gibraltar is a British Overseas Territory. The British Nationality Act 1981 granted Gibraltarians full British citizenship.

Under its current constitution, Gibraltar has almost complete internal democratic self-government through an elected parliament, elected for a term of up to four years. The unicameral parliament presently consists of 17 elected members, and the Speaker who is not elected, but appointed by a resolution of the parliament. The government consists of 10 elected members. The head of state is Queen Elizabeth II, who is represented by the Governor of Gibraltar. The governor enacts day-to-day matters on the advice of the Gibraltar Parliament, but is responsible to the British government in respect of defense, foreign policy, internal security and general good governance. Judicial and other appointments are made on behalf of the Queen in consultation with the head of the elected government.

Gibraltar During and After the Second World War

During World War II, Gibraltar's civilian population was evacuated (mainly to London, but also to parts of Morocco, Madeira and Jamaica) and the Rock was strengthened as a fortress. The naval base and the ships based there played a key role in the provisioning and supply of the island of Malta during its long siege. As well as frequent short runs (known as 'Club Runs') towards Malta to fly off aircraft reinforcements (initially Hurricanes but later, notably from the USN aircraft carrier Wasp, Spitfires), the critical Operation Pedestal convoy was run from Gibraltar in August 1942. This resupplied the island at a critical time in the face of concentrated air attacks from German and Italian forces. Spanish dictator Francisco Franco's reluctance to allow the German Army onto Spanish soil frustrated a German plan to capture the Rock, codenamed Operation Felix. In the 1950s, Franco renewed Spain's claim to sovereignty over Gibraltar and restricted movement between Gibraltar and Spain. Gibraltarians voted overwhelmingly to remain under British sovereignty in the Gibraltar sovereignty referendum, 1967, which led to the passing of the Gibraltar Constitution Order in 1969. In response, Spain completely closed the border with Gibraltar and severed all communication links. The border with Spain was partially reopened in 1982 and fully reopened in 1985 before Spain's accession to the European Community.

In a referendum held in 2002, Gibraltarians rejected by an overwhelming majority (98%) a proposal of shared sovereignty on which Spain and Britain were said to have reached "broad agreement".  The British government has committed itself to respecting the Gibraltarians' wishes. A new Constitution Order was approved in referendum in 2006. A process of tripartite negotiations started in 2006 between Spain, Gibraltar and the UK, ending some restrictions and dealing with disputes in some specific areas such as air movements, customs procedures, telecommunications, pensions and cultural exchange.

In the [2016] British referendum on membership of the European Union 96% of Gibraltarians voted to remain on an 82% turnout.  Spain renewed calls for joint Spanish–British control of the peninsula, which were strongly rebuffed by Gibraltar's Chief Minister.

https://en.wikipedia.org/wiki/Gibraltar

Footnote

The Rock of Gibraltar is entirely contained within the British Overseas Territory of Gibraltar.  None of it is within Spanish borders.